THEIR OLD FORTE: Sione Pouha (left) and Mike DeVito struggled to bring down the Bears' Matt Forte last week as the Jets run defense faltered for the second straight game.Anthony J. Causi

Darrelle Revis makes his living by shutting down opposing wide receivers. But the All-Pro cornerback said he knows shutting down the opposition’s rushing attack is what the Jets’ defense is built on.

“I think with our defense, that’s the number one thing, stopping the run,” Revis said after yesterday’s practice. “We talk about it every week, we talk about it all the time — training camp, OTAs, offseason. We always talk about that, don’t let them run the ball on us.”

Lately, though, the Jets have struggled to hold opposing running backs in check. After allowing just two 100-yard rushers in Rex Ryan’s first 32 games as head coach, the Steelers’ Rashard Mendenhall ran for 99 yards two weeks ago before the Bears’ Matt Forte ran for 113 yards last week.

“It’s a focus every week,” defensive tackle Sione Pouha said. “Even if we play the run well one week, we’re still looking for ways to improve it. We don’t wait for the problem to happen, wait for the numbers to go up and then adjust. We adjust it every week, good or bad.”

So, with tomorrow’s game against the Bills rendered essentially meaningless after the Jets clinched a playoff spot last weekend, the team has focused this week on getting back to basics to shore up its usually stout run defense.

“We are really stressing fundamentals,” Ryan said. “We’ve had more individual periods. We are going back and extending those periods and not (focusing on) the scheme as much as getting our individual techniques back.

“That’s where it is. That’s where it starts and finishes.”

Ryan referenced the Jets’ tackling as an issue he has singled out for more instruction this week.

“It’s a perfect example that you can talk about it all you want, but you have to go out and practice it,” he said. “Our tackling usually is outstanding . . . [but] we haven’t been as good tackling.

“Now, unfortunately, on this level you really can’t go out and tackle [in practice], so you have to talk about it. You have to stress it as far as running through things, wrapping up, grabbing cloth, nose on the football and everything.”

Taking steps to fix the recent flaws in their run defense could be crucial to the team’s chances in the playoffs. If the playoffs started today, the Jets would visit Kansas City in the first round. The Chiefs, behind the combination of Jamaal Charles and former Jet Thomas Jones, lead the league with 167.5 rushing yards per game.

“It’s always important to make sure you play good football, no matter what aspect of the game it is,” linebacker Bart Scott said. “In the playoffs, there’s no room for error. It’s whoever is executing the best is going to have the best chance to win.”

Pouha agreed with Ryan’s assessment that a renewed focus on fundamentals would go a long way toward solving the team’s recent problems stopping the run.

“I think it’s execution,” he said. “Obviously there’s breakdowns – that’s why the numbers are like that. Our resolve is to get back to playing our assignment, playing a little bit tighter, and we’ll get back on track.”